The present invention relates to a camera and a camera accessory interchangeably attachable to the camera such as an interchangeable lens.
Such camera accessories (each hereinafter simply referred to as “an accessory”) receive, in a state of being attached to a camera, supply of power from the camera and perform communication of commands, data or the like with the camera. In order to perform such supply of power and communication, an attachment portion (mount) of the camera and that of the accessory are provided with multiple electrical contacts (each hereinafter simply referred to as “a contact”) in which paired ones are brought into contact with each other to establish electrical connection. Moreover, as a method of the attachment (coupling) of the camera and the accessory, bayonet coupling is often used in which the mounts of the camera and accessory are relatively rotated to cause bayonet claws provided in the respective mounts to engage with each other.
Japanese Patent Laid-Open No. 62-195633 discloses a camera and an interchangeable lens as an accessory respectively having a camera side mount and a lens side mount that are coupled with each other by the bayonet coupling method. In a coupling completion state after relative rotation of the camera side and lens side mounts, each of multiple camera side contact pins provided in the camera side mount makes contact with corresponding each of multiple lens side contact pins (contact surfaces) provided in the lens side mount. The camera side contact pins and the lens side contact pins are respectively held by a camera side contact base provided in the camera side mount and by a lens side contact base provided in the lens side mount. The camera side contact base is provided with hole portions into which the camera side contact pins are inserted to be held thereby, and each camera side contact pin is biased in a direction of protruding from the hole portion (that is, in a protruding direction) by a contact spring disposed between the camera side contact pin and a printed wiring board placed at bottom of the hole portion. The lens side contact pins are fixedly held by the lens side contact base.
Recently, in order to reduce weight of the camera, its mount is produced by resin molding. Such a mount produced by resin molding is hereinafter referred to as “a molded mount”. Furthermore, in order to reduce thickness of the camera, the contact spring biasing the camera side contact pin in the protruding direction is formed using a leaf spring.
In addition, the camera side and accessory (lens) side contact pins include: power supplying contact pins for supplying, from the camera to the accessory, source power to drive an actuator provided in the accessory; and controlling contact pins for sending and receiving, between the camera and the accessory, signals to control the accessory.
The camera and accessory each provided with such a mount (particularly, a molded mount) holding the contact pins have the following problems.
FIG. 19 shows falling of a camera 401 to ground 405; an interchangeable lens 402 as an accessory is attached to the camera 401. When the camera 401 falls to the ground 405, a front edge of the interchangeable lens 402 heavier in weight than the camera 401 is highly likely to first hit the ground 405. In this case, a maximum external force acting to a lowest portion of the mounts coupling the camera 401 and interchangeable lens 402 so as to tear the coupled mounts apart from each other is generated. Therefore, it is desirable to provide a bayonet claw in a phase including the lowest portion of each of the camera side and lens side mounts and to provide, in that phase, a fastening portion of each of the camera side and lens side mounts respectively fastened to a camera body (chassis of the camera 401) and a lens body (chassis of the interchangeable lens 402) by using a fastening screw.
However, providing the camera side contact pin to a same position as that of the fastening screw in a circumferential direction of the mount and using the leaf spring as the contact pin biasing the camera side contact pin in the protruding direction needs to increase a pitch of the camera side contact pins because it is necessary to dispose the leaf spring so as to avoid interference with the fastening screw. Such a configuration increases an angular range occupied by the camera side contact pins (that is, a contact occupied angular range) in the camera side mount, which impedes miniaturization of the camera.
On the other hand, the camera is provided with a motor as an actuator to drive a shutter or the like; the motor generates noise. The noise affects control of the accessory, which causes erroneous operation of the accessory.
In addition, wiring is made using a flexible board or the like from tha power supply provided in the camera to the power supplying contact pin. However, a long length wiring is likely to increase electrical loss due to wiring resistance.